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The purpose of this module is to explain session tracking using hidden fields, and to compare a servlet with a JSP to accomplish the same objective.

Table of contents


This module is one in a collection of modules designed for teaching INEW 2338 Advanced Java (Web) at Austin Community College in Austin, TX. The purpose of this module is to explainsession tracking using hidden fields, and to compare a servlet with a JSP to accomplish the same objective.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figures and Listings while you are reading about them.


  • Figure 1 . The servlet user interface at startup.
  • Figure 2 . Browser display for Tom, Dick, and Harry.
  • Figure 3 . Hidden fields in the servlet output.


  • Listing 1 . Beginning of the servlet class.
  • Listing 2 . Get and save the hidden values from the browser page.
  • Listing 3 . Get and save user input data.
  • Listing 4 . Begin constructing the HTML output data.
  • Listing 5 . Begin the HTML code for an HTML form.
  • Listing 6 . An input field and a submit button.
  • Listing 7 . Beginning of the list of names.
  • Listing 8 . Display the historical data and also save it on the browser.
  • Listing 9 . Display most recent value and also store it on the browser.
  • Listing 10 . Create basic web page structure.
  • Listing 11 . A JSP scriptlet.
  • Listing 12 . The body of the for loop.
  • Listing 13 . Another scriptlet.
  • Listing 14 . Another JSP expression tag.
  • Listing 15 . Terminating scriptlet and HTML code.
  • Listing 16 . The servlet program named Java4550a.java.
  • Listing 17 . The JSP program named Java4550a.jsp.

General background information

A stateless protocol

The HTTP protocol is a relatively simple request/response protocol that does not retain historical information from one client request to the next. In otherwords, each request is a new start insofar as the HTTP server is concerned. (HTTP is sometimes referred to as a "stateless" protocol.) However, historical information can be very important. The maintenance ofhistorical information is often referred to as "session tracking."

Session tracking

Session tracking is very important for many web applications including web commerce and web games. Therefore, this and the next several modules will show you some of the ways thatyou can accomplish session tracking using servlets and JSP.

Web commerce

Perhaps the most common example of the need for session tracking is with a web commerce application involving a shopping cart. The customer (client) downloads various pages from a vendor catalog, selecting items, and placing themin a shopping cart. At some point, the customer decides either to purchase the items or abandon the shopping trip.

If the customer decides to purchase the items in the cart, the web application must have a record of all the items in the cart. Furthermore, thatrecord must be associated with that particular customer so that the sale can be consummated.

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
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for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
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I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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how did you get the value of 2000N.What calculations are needed to arrive at it
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